How do rock candy form?

Rock candy formation involves a process called crystallization, which occurs due to the growth and interlocking of sugar crystals when a supersaturated sugar solution cools. Here's a step-by-step explanation:

1. Sugar Syrup: Rock candy starts with boiling a mixture of sugar and water to form a concentrated syrup. The ratio of sugar to water determines the resulting supersaturation.

2. Supersaturated Solution: By boiling, the hot sugar syrup can dissolve a higher amount of sugar than it typically can at room temperature, creating a supersaturated solution.

3. Cooling: The hot syrup is then allowed to cool. As it cools, the solubility of sugar in the solution decreases, causing an excess of sugar molecules. This sets the stage for crystal growth.

4. Seed Crystal: To initiate crystallization, a "seed crystal" is typically introduced. It can be a small piece of sugar crystal or another inert object like a thread or a string.

5. Crystal Growth: The seed crystal becomes a base for sugar molecules to attach and grow, forming a larger crystal over time. The process is driven by the attraction between the molecules of the seed crystal and sugar molecules in the solution.

6. Crystal Shape: As the crystal continues to grow, it takes on a specific shape determined by its molecular structure. Rock candy crystals typically form as large and distinctive single crystals, bounded by flat faces.

7. Multiple Crystals: If multiple seed crystals are introduced or crystallization centers develop spontaneously, multiple rock candy crystals will form simultaneously in the solution.

8. Time: The process of rock candy formation is gradual and requires patience. It can take several days to weeks for the crystals to grow to their full size, depending on the temperature and concentration of the sugar syrup.

9. Harvesting: Once the crystals have grown to the desired size, they can be carefully removed from the solution. The crystals may then be dried or left as is, revealing the beautiful, transparent nature of rock candy.

By carefully controlling the process, including the temperature, concentration, and the introduction of seed crystals, rock candy can be grown at home and enjoyed as a delightful treat.